Implant Pose Determination in Medical Imaging

1. A method for determining implant pose, the method comprising: segmenting data representing an implant in a patient from an x-ray image of the patient; comparing the segmented data representing the implant with representations in a database of representations of a model of the implant, the representations being compared with the segmented data each being of the model of the implant in different poses relative to an x-ray source; identifying a match of the segmented data representing the implant to a first one of the different poses of the model of the implant, the match identified based on the comparing; determining the implant pose in the x-ray image of the patient from the first pose of the model of the implant.

2. The method of claim 1 wherein segmenting comprises thresholding the x-ray image and locating a largest connected region from the pixels remaining after the thresholding.

3. The method of claim 1 wherein segmenting comprises applying a machine-trained detector.

4. The method of claim 1 wherein segmenting comprises segmenting from the x-ray image, the x-ray image comprising a projection to an image plane.

5. The method of claim 1 wherein comparing comprises calculating a similarity of the segmented data representing the implant with the model in the different poses.

6. The method of claim 1 wherein comparing comprises comparing the segmented data representing the implant with the model in the different poses comprising digital reconstruction radiographs of the model.

7. The method of claim 1 wherein comparing comprises saliency-based global matching.

8. The method of claim 7 wherein saliency-based global matching comprises: directionally filtering the segmented data at different scales; determining differences between the segmented data at the different scales; and weighting the comparing as a function of the differences.

9. The method of claim 1 wherein identifying the match comprises identifying the first pose as more similar to the segmented data than others of the different poses.

10. The method of claim 1 wherein comparing and identifying are performed in a coarse-to-fine search pattern.

11. The method of claim 1 wherein determining the implant pose comprises aligning the x-ray image with the model.

12. The method of claim 1 further comprising: displaying the x-ray image with an overlay of the model, the overlay of the model being in the first pose.

13. A non-transitory computer readable storage medium having stored therein data representing instructions executable by a programmed processor for determining implant pose, the storage medium comprising instructions for: segmenting an implant portion of an x-ray image; searching a database of radiographic reconstructions for a representation of an implant, the radiographic reconstructions corresponding to different views of the representation of the implant; matching the implant portion with a first radiographic reconstruction of the radiographic reconstructions from the database where the matching is closer for the first radiographic reconstruction than for others of the radiographic reconstructions of others of the different views; and determining the implant pose within the x-ray image based on a first view of the different views associated with the first radiographic reconstruction.

14. The non-transitory computer readable storage medium of claim 13 wherein segmenting comprises extracting a portion of the x-ray image representing the implant.

15. The non-transitory computer readable storage medium of claim 13 wherein searching comprises searching in a coarse-to-fine search pattern for performing the matching.

16. The non-transitory computer readable storage medium of claim 13 wherein matching comprises matching weighted by saliency of the implant portion of the x-ray image.

17. The non-transitory computer readable storage medium of claim 13 wherein determining comprises determining the implant pose as a pose of the representation of the implant in the first radiographic reconstruction.

18. A system for aligning a three-dimensional model of an implant with a view of the implant in a medical image, the system comprising: a memory storing two-dimensional x-ray image representations of the implant from different directions; and a processor configured to select a first one of the different directions as a function of similarities between an x-ray image of the implant and each of different ones of the two-dimensional x-ray image representations of the implant, the first direction selected for one of the x-ray image representation with a greater similarity.

19. The system of claim 18 wherein the processor is configured to extract a portion of the x-ray image corresponding to the implant, determine saliency of the portion, and weight the selection based on the saliency.

20. The system of claim 18 wherein the memory stores at least one thousand of the two-dimensional x-ray image representations of the implant, the two-dimensional x-ray image representations comprising digital reconstruction radiographs.